I. Field of the Invention
This invention relates generally to the design of a wheel chair frame and more specifically to a folding-type wheel chair frame having a portion thereof supported by telescoping posts which thereby enables the width of the chair to be adjusted, while continuing to use conventional "X" cross members to permit collapsing of the chair in a single assembly.
II. Description of Prior Art
A typical prior art collapsible wheel chair frame over which the present invention is deemed to be an improvement is described in the McClintock U.S. Pat. No. 3,331,614. The frame of the McClintock Patent comprises first and second sides coupled together by pivoting cross members. The cross members connect from a bottom strut on a first side to a vertically moving seat support member on the opposite side. The chair is collapsed by moving one side towards the other and in doing so, the seat support rails on either side move upward. A means is provided for the invalid to adjust the width of his chair by turning a crank operated threaded screw which couples the slidable seat frame to the stationary arm rests.
It is to be especially noted that in the frame design disclosed in the McClintock Patent the height of the seat is inversely related to the width of the chair. That is, the wider the chair, the lower the seat and vice versa. It is also to be noted that the height of the arm rests with respect to the seat is also a function of the chair width.
Because of the dimensions of the human body, for maximum comfort, the distance between the arm rests and the seat should remain constant independent of the overall width of the chair. Then too, most invalids prefer not to sit too high in the chair because of a fear of tipping due to the high center of gravity.
The wheel chair frame designed in accordance with the teachings of the present invention allows the seat height with respect to the arm rests to remain constant independent of chair width when in its operable position. Furthermore, the seat height with respect to the ground also remains constant. However, when it is desired to collapse the folding wheel chair for transportation or the like, this can be accomplished quite readily.